Cameras, for example monitoring cameras, are used in many different applications, both indoors and outdoors. The technical field relating to cameras is undergoing continuous development and improvement which have led to, for example, larger image resolutions, improved optics, and new functionalities.
A larger image resolution is obtained by a large image sensor with an increased number of pixels. However, a camera with such an image sensor is also more sensitive to misalignment between the image sensor and the optics unit which provides the image sensor with light representing the scene to be monitored. That is, a higher pixel intensity in the image sensor yields that a misalignment between the optics unit and the sensor board has a larger impact on the resulting image quality. It is thus increasingly important to ensure a precise alignment between the optics unit and the image sensor.
A commonly used alignment technique for camera manufacturing today is active alignment. Here, a sensor board, comprising an image sensor, and an optics unit are adjusted in relation to each other based on images captured during the alignment in order to optimize quality characteristics (such as focus and centering of the light axis on the image sensor) of the resulting image. In many active alignment techniques UV curing glue is used to fix the image sensor to the optics unit. The UV curing glue is applied between the image sensor and the optics unit. Thereafter, the alignment, (i.e. positioning of the image sensor and the optics unit relative each other), is performed. Finally, when the alignment is considered satisfactory, the glue is exposed to UV light whereby it solidifies and fixes the positions of the image sensor and optics unit relative each other. However, the use of UV curing glue has a number of drawbacks including the need for storing the glue, the need for application of the glue which makes the process complex, outgassing, and that the curing of the glue is permanent and thus cannot be reversed. Also, application of UV light may require specific knowledge in order to ensure correct hardening, for example regarding wave length of the UV light, intensity output, curing time, curing depth, etc. Further, in known active alignment processes, such as the one using UV curing glue, dust may enter the area between the image sensor and the optics unit and give rise to image deteriorations. At least a part of the mounting process, including the active alignment process, must therefore be performed in a clean environment, for example in a clean room adapted for the process.
Evidently, there is a strong need for improvements relating to alignment between an optics unit and a sensor board in a camera arrangement.